Stacked sump pumps

[Smarty]

I've just had an unexpected failure of my 6 year old sump pump, resulting in a fair amount of rain water in my basement.

In considering replacements, the thought occurs to me that a 2nd redundant pump placed above the replacement primary pump would hopefully prevent this situation from occurring again.

The sump is 18 inches in diameter and 28 inches deep, enough space (I think) to mount two pumps, one above the other.

I am a bit uncertain as to how, if at all, I should use one-way valves in the discharge plumbing to prevent backflow.

The discharge line is 1-1/4inch NPT. I am wondering if just using a "tee" to join the two discharge lines would be sufficient?

Any thoughts would be most appreciated and thank you in advance.

Happy Thanksgiving to a terrific group of very knowledgeable and helpful people!

Smarty

[Joseph Meehan]

You will need a valve for each pump.

[DanG]

It is standard and normal to have 2 pumps. They can be installed side by side with an alternating A/B switch that fires the opposite one at each startup or can be designed to give each pump the same operating hours. The pumps can also be arranged in series or in parallel . They are rigged to both come on when necessary. All of the switching and mechanics are readily available. Each pump has its own check valve. Here is a site that offers a package system:

[Meat Plow]

Consider a backup pump that runs off of a charge maintained battery.

[Doug Miller]

That would protect you from a pump failure, yes -- but what about a power failure? For your second pump, consider something with a backup battery, such as Basement Watchdog or Ace in the Hole.

Or side by side, which is almost certainly easier.

You should always use one-way valves.

I'd use a wye instead of a tee (less flow resistance for the arm on the side).

Having two backflow preventers, one per pump, installed on the pump side of the wye, will make installation (and later service) much easier, as opposed to a single backflow preventer on the discharge side of the wye -- provided you use the type with rubber couplings and hose clamps, not the ones with threaded fittings.

[Smarty]

Thanks all for the great advice. I am going out today to see what the local stores have available. Unfortunately there has been a lot of rain here so I can't postpone my decision too long.

Smarty